[PATCH v2] media: i2c: ds90ub960: use guard(mutex) in simple register accessors

[Laurian Iacob]

Convert the manual mutex_lock()/mutex_unlock() of reg_lock in
ub960_read(), ub960_write(), ub960_update_bits() and ub960_read16() to
guard(mutex), and in ub960_reset() to scoped_guard(mutex).

With the lock released automatically on return, the error paths can
return directly, which drops the out_unlock label from ub960_read() and
ub960_read16().

The rxport, txport and indirect register accessors are left unchanged,
as they still rely on goto-based error handling and include/linux/cleanup.h
asks that goto and cleanup helpers not be mixed within one function.

No functional change intended.

Signed-off-by: Laurian Iacob <laurian.iacob@xxxxxxxxx>
---

Notes:
    Changes in v2:
     - Fix ub960_update_bits() always returning 0 when regmap_update_bits()
       fails
     - Don't convert the rxport/txport/indirect accessors, which still use
       goto-based error handling (see include/linux/cleanup.h)
     - Drop unrelated blank-line changes
     - Reword subject and changelog to match the reduced scope
    
    v1: https://lore.kernel.org/all/20261106114859.1579-1-laurian.iacob@xxxxxxxxx/
    
    Compile-tested only (W=1); no DS90UB960/954 hardware available.

 drivers/media/i2c/ds90ub960.c | 68 +++++++++++++++--------------------
 1 file changed, 28 insertions(+), 40 deletions(-)

diff --git a/drivers/media/i2c/ds90ub960.c b/drivers/media/i2c/ds90ub960.c
index 7d7ba6d349fc..ee410bae1216 100644
--- a/drivers/media/i2c/ds90ub960.c
+++ b/drivers/media/i2c/ds90ub960.c
@@ -748,24 +748,20 @@ static int ub960_read(struct ub960_data *priv, u8 reg, u8 *val, int *err)
 	if (err && *err)
 		return *err;
 
-	mutex_lock(&priv->reg_lock);
+	guard(mutex)(&priv->reg_lock);
 
 	ret = regmap_read(priv->regmap, reg, &v);
 	if (ret) {
 		dev_err(dev, "%s: cannot read register 0x%02x (%d)!\n",
 			__func__, reg, ret);
-		goto out_unlock;
+		if (err)
+			*err = ret;
+		return ret;
 	}
 
 	*val = v;
 
-out_unlock:
-	mutex_unlock(&priv->reg_lock);
-
-	if (ret && err)
-		*err = ret;
-
-	return ret;
+	return 0;
 }
 
 static int ub960_write(struct ub960_data *priv, u8 reg, u8 val, int *err)
@@ -776,19 +772,18 @@ static int ub960_write(struct ub960_data *priv, u8 reg, u8 val, int *err)
 	if (err && *err)
 		return *err;
 
-	mutex_lock(&priv->reg_lock);
+	guard(mutex)(&priv->reg_lock);
 
 	ret = regmap_write(priv->regmap, reg, val);
-	if (ret)
+	if (ret) {
 		dev_err(dev, "%s: cannot write register 0x%02x (%d)!\n",
 			__func__, reg, ret);
+		if (err)
+			*err = ret;
+		return ret;
+	}
 
-	mutex_unlock(&priv->reg_lock);
-
-	if (ret && err)
-		*err = ret;
-
-	return ret;
+	return 0;
 }
 
 static int ub960_update_bits(struct ub960_data *priv, u8 reg, u8 mask, u8 val,
@@ -800,19 +795,18 @@ static int ub960_update_bits(struct ub960_data *priv, u8 reg, u8 mask, u8 val,
 	if (err && *err)
 		return *err;
 
-	mutex_lock(&priv->reg_lock);
+	guard(mutex)(&priv->reg_lock);
 
 	ret = regmap_update_bits(priv->regmap, reg, mask, val);
-	if (ret)
+	if (ret) {
 		dev_err(dev, "%s: cannot update register 0x%02x (%d)!\n",
 			__func__, reg, ret);
+		if (err)
+			*err = ret;
+		return ret;
+	}
 
-	mutex_unlock(&priv->reg_lock);
-
-	if (ret && err)
-		*err = ret;
-
-	return ret;
+	return 0;
 }
 
 static int ub960_read16(struct ub960_data *priv, u8 reg, u16 *val, int *err)
@@ -824,24 +818,20 @@ static int ub960_read16(struct ub960_data *priv, u8 reg, u16 *val, int *err)
 	if (err && *err)
 		return *err;
 
-	mutex_lock(&priv->reg_lock);
+	guard(mutex)(&priv->reg_lock);
 
 	ret = regmap_bulk_read(priv->regmap, reg, &__v, sizeof(__v));
 	if (ret) {
 		dev_err(dev, "%s: cannot read register 0x%02x (%d)!\n",
 			__func__, reg, ret);
-		goto out_unlock;
+		if (err)
+			*err = ret;
+		return ret;
 	}
 
 	*val = be16_to_cpu(__v);
 
-out_unlock:
-	mutex_unlock(&priv->reg_lock);
-
-	if (ret && err)
-		*err = ret;
-
-	return ret;
+	return 0;
 }
 
 static int ub960_rxport_select(struct ub960_data *priv, u8 nport)
@@ -1272,12 +1262,10 @@ static int ub960_reset(struct ub960_data *priv, bool reset_regs)
 	if (ret)
 		return ret;
 
-	mutex_lock(&priv->reg_lock);
-
-	ret = regmap_read_poll_timeout(priv->regmap, UB960_SR_RESET, v,
-				       (v & bit) == 0, 2000, 100000);
-
-	mutex_unlock(&priv->reg_lock);
+	scoped_guard(mutex, &priv->reg_lock) {
+		ret = regmap_read_poll_timeout(priv->regmap, UB960_SR_RESET, v,
+					       (v & bit) == 0, 2000, 100000);
+	}
 
 	if (ret)
 		dev_err(dev, "reset failed: %d\n", ret);
-- 
2.43.0